<!DOCTYPE html>
<html>
<head>
    <title></title>
    <script src="https://unpkg.com/react@16/umd/react.development.js"></script>
    <script src="https://unpkg.com/react-dom@16/umd/react-dom.development.js"></script>
    <script src="https://unpkg.com/babel-standalone@6.15.0/babel.min.js"></script>
</head>
<body>
<div id="root"></div>
<script type="text/babel">
    var n = 0;
    function test() {
        const element = (
            <div>
                <h1>Hello,World</h1>
                <h1>test() runs {++n} time</h1>
            </div>
        );
        ReactDOM.render(element, document.getElementById('root'));
    }
    //设置定时器进行循环
    setInterval(test, 1000);
</script>
</body>
</html>